Optical measurements are performed to determine physical properties of tissues. In those measurements, light is irradiated on a tissue, interacts with the tissue and light coming back is detected and analyzed, so as to deduce therefrom properties of the tissue. Those measurements are used, for instance, for cancer diagnosis of a living tissue, by discrimination of cancerous and normal tissues.
Light coming back from the probed region of the tissue contains information useful for the analysis, related to the optical properties of the probed region of the tissue. Many techniques show that there exists a need of determining, besides this information, the scattering and/or absorption properties of the tissue nearby the probed region of the tissue. Indeed, for instance in cancer detection, changes in the scattering and/or absorption coefficients is an important signature to discriminate cancerous tissue from normal tissue.
WO 2005/029051 discloses a method and device for determining a physical feature of a medium, comprising:                producing radiation with a light source;        placing a probe on a sample of the medium, the probe comprising a first optical fiber having a first diameter, and at least a second optical fiber having a second diameter;        sending light coming from the light source, through the first optical fiber;        collecting first backscattered radiation through the first optical fiber and second backscattered radiation through the second optical fiber;        producing a first signal based on the first backscattered radiation, and a second signal based on the second backscattered radiation;        determining a measured differential backscatter signal as a function of wavelength using the first and second signals, characterized by        calculating the physical feature by curve fitting the measured differential backscatter signal to a backscatter function, in which the backscatter function is a function of a mean free path of photons.        
However, such a method or device implies using two fibers positioned alongside each other, which is not very practical. Furthermore, with the use of fibers, the tissue cannot be scanned, but only probed point by point, in the superficial layers such as the epithelial layer.